三角翼涡破裂非定常特性实验研究

Experimental investigations on the unsteady characteristics of vortex breakdown over delta wing

本文依据染色液流动显示结果,通过子波和频谱分析,探讨了70°三角翼前缘涡涡核轴向速度的变化规律及其子波特性、涡破裂位置的非定常特性,指出涡破裂点位置的变化属于低频高幅振荡,这主要是左右涡之间的相互作用造成的,当两个涡的时间平均涡破裂点位置彼此靠得更近时,相应的振荡就更大一些,此外本实验得到涡破裂位置振荡的折合频率在St=0.2以内。

Based on the dye visualization experimental results, the variation of vortex cores velocity along vortex axis and their wavelet characteristics and the unsteadiness of the vortex breakdown position were investigated for flowing over 70 deg delta wing. The multi-scale decomposition of signals of vortex core velocity can be achieved through wavelet analysis, significant high frequency signal occurred at vortex breakdown location. Spectral analysis was used to quantify the unsteady behavior of vortex breakdown location obtained from visualization. It was pointed out that the variation of vortex breakdown position belonged to low frequency oscillation, which was caused by the interaction between the right and left leading edge vortices. When the distance for the mean vortex breakdown position of the two vortices became close, the corresponding oscillation tended to become violent. Moreover, the reduced frequency of this oscillation is less than 0.2.